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Re-examination of the neptunium-hydrogen system [electronic resource].

Published
Los Alamos, N.M. : Los Alamos National Laboratory, 1986.
Oak Ridge, Tenn. : Distributed by the Office of Scientific and Technical Information, U.S. Dept. of Energy.
Physical Description
Pages: 15 : digital, PDF file
Additional Creators
Los Alamos National Laboratory and United States. Department of Energy. Office of Scientific and Technical Information
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Summary
New P-C-T studies have been made on the Np + H system, using ultrapure double-electrorefined metal. Measurements were carried out over six orders of magnitude in pressure, from 0.0005 to 70 bar. The solubility of hydrogen was found to be very low. Metal-dihydride plateaus were flat, the two-phase boundary extremely sharp; this occurred at the unusual value H/Np approx. = 2.13. The dihydride lattice expanded upon addition of hydrogen, also in contrast to other trivalent rare-earth and actinide hydrides. A rather narrow cubic/hexagonal two-phase region was found (only on dehydriding), together with an even narrower hexagonal phase region. The effect of the beta-gamma transition at 576/sup 0/C could be seen both in the curvature of the phase boundary and the partial molal enthalpy values. Entropies of formation were found to be nearly constant. The data below 576/sup 0/C can be described by the equation ln P(bar) = 13.297 - 13233/T(K), giving values, adjusted for the reaction 0.93 Np + H/sub 2/ = 0.93 NpH/sub 2.13/: ..delta..H/sub f/(NpH/sub 2.13/) = 118.3 kJ/mol (28.27 kcal/mol), and ..delta..S/sub f/(NpH/sub 2.13/) = 118.4 J/mol-K (28.3 cal/mol/-K). Integral heats and entropies are calculated for the entire system, and the unusual phase behavior is discussed in terms of the electronic structure.
Report Numbers
E 1.99:la-ur-86-1401
E 1.99: conf-8605114-1
conf-8605114-1
la-ur-86-1401
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Note
Published through SciTech Connect.
01/01/1986.
"la-ur-86-1401"
" conf-8605114-1"
"DE86010197"
Properties and applications of metal hydrides, Maubuisson, France, 25 May 1986.
Rebizant, J.; Ward, J.W.; Bartscher, W.
Funding Information
W-7405-ENG-36
View MARC record | catkey: 14458853